Fasting has become an ever increasingly popular dieting trend used for predominantly weight loss but also for general health, so let’s get the facts straight!
Fasting in of itself is simply a prolonged period in which we do not consume any food and or calorie-containing liquid. There are a variety of fasting protocols ranging from intermittent fasting/time restricted feeding (that is, fasting for most of the day and having a small window of time in which you can eat) to whole day (or longer!) fasts.
Fasting has several associated benefits. As it relates to dieting, the obvious being that it may result in a calorie restricted state. If we reduce the time and/or days that we can eat, we are more likely to eat a quantity of food that would put us in a calorie deficit and therefore initiate weight loss. Of course, calories are simply the energy we get from food. If we consume less calories than the amount we require to maintain our weight, we are considered to be in a calorie deficit which will facilitate weight loss.
What are the other major benefits of fasting?
Reduce blood pressure
Increased insulin sensitivity and has been associated with improving, if not reversing, the metabolic syndrome (a cluster of symptoms which can lead to heart disease) in animal models. The challenge is that in human, the group we typically see metabolic syndrome in (those who are overweight/obese) may find protocols like fasting difficult to maintain
Time restricted feeding has been shown to have benefits in individuals suffering from IBS
Increased anabolism (building stuff up). When we fast for periods of time our body becomes more sensitive to the next source of nutrients it takes in (similar to exercise). We can exploit this by targeting a high protein intake in addition to a serving of carbohydrate if the goal is to improve lean body mass and or recover from exercise
Improved cognitive function
Fasting, which results in a low glycogen state/depleted state, may enhance our adaptation to aerobic training stress (also known as mitochondrial biogenesis)